Randall, Geoffrey
Crest Publishing House, 2001
Buku Teks
Morse, Stephen A.
Crest Publishing House, 2001
Buku Teks
Kartajaya, Hermawan
Mizan, 2006
Buku Teks
Lancaster, Greoff
Crest, 2001
Buku Teks
edited by Edward C. Bursk and John F. Chapman
New American Library, 1964
Buku Teks